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Finding the Fourth Proportional to 85.98, 128.88 and 68.79

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Solution

The fourth proportional to 85.98, 128.88 and 68.79 is: 103.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.98 : 128.88 = 68.79 : x
  2. Step 2: Convert to fraction form
    85.98/128.88 = 68.79/x
  3. Step 3: Cross multiply
    85.98x = 128.88 × 68.79
  4. Step 4: Simplify right side
    85.98x = 8,865.66
  5. Step 5: Solve for x
    x = 8,865.66/85.98
  6. Step 6: Final answer
    x = 103.11

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.